[erlang-questions] Dedicated mnesia nodes or fragmented nodes?

Chandru <>
Thu Mar 26 06:47:45 CET 2009

2009/3/26 ryeguy <>

> I have 2 cluster layouts in mind, and was wondering what the pros and
> cons are for each:
> 1) Nodes are either worker nodes, or mnesia nodes. Mnesia nodes
> contain only tables and do nothing else; worker nodes do all the heavy
> lifting.

Pros: You have more flexibility. You can take database nodes in/out without
any impact to your processing capacity (upto a point). Database upgrades are
less stressful.
Cons: You have more nodes to manage. Every database lookup is an RPC call.

> 2) All hybrid nodes - all nodes do heavy lifting, and each node has a
> mnesia table fragment on it.
Pros: Lesser management overhead. Even if there are partitioned networks,
the worker might be able to service requests for which it holds data
locally. Not all database lookups are RPC calls.
Cons: You lose a bit of flexbility and upgrades become more complex.

If you have a very large database, I would recommend (1). It works for me.

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